Abstract

Thresholds for photophobia (light-induced discomfort) were determined at wavelengths from 440 to 640 nm for three subjects. Photophobia was assessed by means of electromyography, which was used to measure subjects’ level of squinting. After correction for absorption by macular pigment and the ocular media, subjects’ functions displayed a trend of increasing sensitivity with decreasing wavelength. We propose that the corrected function is indicative of increased sensitivity to potential retinal damage by short-wavelength light. It is therefore suggested that photophobia serves a function of biological protection. Results also suggest that photophobia is significantly mitigated by macular pigment in the short wavelengths.

J. B. de Boer, “Visual perception in road traffic and the field of vision of the motorist,” in Public Lighting, J. B. de Boer, ed. (Phillips Technical Library, Eindhoven, The Netherlands, 1968), pp. 11–96.

de Boer, J. B.

J. B. de Boer, “Visual perception in road traffic and the field of vision of the motorist,” in Public Lighting, J. B. de Boer, ed. (Phillips Technical Library, Eindhoven, The Netherlands, 1968), pp. 11–96.

J. B. de Boer, “Visual perception in road traffic and the field of vision of the motorist,” in Public Lighting, J. B. de Boer, ed. (Phillips Technical Library, Eindhoven, The Netherlands, 1968), pp. 11–96.

Top panel: Supplemental wavelengths (440–500 nm, 10-nm steps) added to existing P(λ) functions (subjects JS and AW). Subject NK, tested on six wavelengths, is plotted for comparison. Functions are normalized to 500 nm. Bottom panel: P(λ) functions, based on the scaling procedure described in the text, for JS and AW. Functions are normalized to 500 nm.

Average of corrected P(λ) functions (subjects JS and AW) compared with absorption spectra of retinal melanin, melanopsin, and metarhodopsin II. Pigments have been adjusted on the Y axis to allow for a composite best fit to P(λ).